Photographic materials containing hydrophilic colloids

ABSTRACT

PHOTOGRAPHIC EMULSIONS HAVING A BINDING AGENT COMPRISING GELATIN AND AT LEAST TWO OTHER HYDROPHILIC COLLOIDS, ONE BEING CARBOXYMETHYLATED PROTEIN, EXHIBIT IMPROVED PHOTOGRAPHIC PROPERTIES AND ARE PARTICULARLY USEFUL WHEN PROCESSED IN AUTOMATIC PROCESSING EQUIPMENT. PHOTOGRAPHIC ELEMENTS COMPRISING SILVER HALIDE AND A LAYER HAVING SAID BINDING AGENT UPON A SUITABLE SUPPORT ARE ALSO DISCLOSED.

United States Patent 3,589,908 PHOTOGRAPHIC MATERIALS CONTAINING HYDROPHILHC COLLOIDS James Plakunov, Rochester, N.Y., assignor to Eastman Kodak Company, Rochester, NY. No Drawing. Filed Nov. 8, 1965, Ser. No. 506,831 Int. Cl. C03c 1/10 U.S. Cl. 96-107 17 Claims ABSTRACT OF THE DISCLOSURE Photographic emulsions having a binding agent comprising gelatin and at least two other hydrophilic colloids, one being carboxymethylated protein, exhibit improved photographic properties and are particularly useful when processed in automatic processing equipment. Photographic elements comprising silver halide and a layer having said binding agent upon a suitable support are also disclosed.

This invention relates to photographic materials, their preparation and use. In one of its aspects, this invention relates to a means for obtaining photographic emulsions and elements having improved photographic and physical properties. In another of its aspects, this invention relates to improved photographic silver halide emulsions and elements containing a unique combination of at least three hydrophilic colloids.

The use of gelatin, a hydrophilic colloid, as the binding agent or vehicle in photographic silver halide emulsions and elements is well known. Attempts have been made to substitute various synthetic and natural materials for all or a part of the gelatin to improve certain photographic and physical properties. However, improvement in one property is generally achieved at the expense of another and often more important property. For example, organic hydrophilic colloids such as water soluble polyacrylamides have been used to improve the contrast of silver halide emulsions. However, emulsion layers containing such materials tend to have reduced resistance to abrasion. Good resistance to abrasion is, of course, very desirable in ph0tographic materials which are subjected to abrasion during handling, and particularly during processing in automatic processing equipment. carboxymethylated proteins have also been used as the sole replacement for part of the gelatin in binding agents to obtain improved photographic properties such as improved sensitivity and contrast. However, in the past, this has not achieved a combination of good speed and contrast with high resistance to abrasion, which is particularly desirable in photographic materials intended for processing in automatic processing equipment, e.g., equipment of the type described in Russell et al. U.S. Pat. 3,147,090, issued Sept. 1, 1964, and U.S. Pat. 3,025,779, issued Mar. 20, 1962.

It is evident, therefore, that it would be desirable to provide the art with a means for obtaining photographic emulsions and elements which exhibit a good level of photographic properties such as sensitivity and contrast, as well as physical properties such as resistance to abrasion.

Accordingly, it is an object of this invention to provide photographic emulsions and elements exhibiting improved properties.

Another object of this invention is to provide a means for obtaining photographic emulsions and elements exhibiting an improved combination of photographic sensitivity and contrast together with good resistance to abrasion.

Another object of this invention is to provide photographic elements which, due to their improved resistance to abrasion, are particularly suited for processing in automatic processing equipment.

3,589,908 Patented June 29, 1971 Still another object of this invention is to provide photographic silver halide emulsions and elements having a binding agent comprising a unique combination of gelatin and at least two other hydrophilic colloids.

Still another object of this invention is to provide photographic elements having a unique binding agent and arrangement of layers which makes it possible to obtain improved photographic and physical properties.

Still another object of this invention is to provide a photographic element containing a gelatin silver halide emulsion layer which can be processed to high speed and contrast in automatic processing equipment and which layers are resistant to abrasion and other physical imperfections.

Other objects of this invention will become apparent from an examination of the specification and claims which follow.

In accordance with this invention it has been found that the above and other objects can be attained by using the combination of carboxymethylated protein and at least one difierent hydrophilic colloid with gelatin in a binding agent in photographic emulsions and elements. One embodiment of this invention relates to a photographic silver halide emulsion having a binding agent comprising gelatin and at least two other hydrophilic colloids, one of said other hydrophilic colloids being carboxymethylated protein at a concentration in the range of about 2.5 to about by weight, based on binding agent.

Another embodiment of this invention relates to a photographic element comprising a support and a layer having a binding agent comprising gelatin and at least two other hydrophilic colloids, one of said other hydrophilic colloids being carboxymethylated protein at a concentration in the range of about 2.5 to about 50%, by weight, based on binding agent.

Another embodiment of this invention relates to a photographic element comprising (1) a support, (2) a photographic silver halide emulsion layer having a binding agent comprising gelatin and at least two other hydro philic colloids, one of said other hydrophilic colloids being carboxymethylated protein at a concentration in the range of about 2.5 to about 50%, by weight, based on binding agent and (3) contiguous to said emulsion layer, a layer having a binding agent comprising gelatin and at least two other hydrophilic colloids, one of said other hydrophilic colloids being carboxymethylated protein at a concentration in the range of about 2.5 to about 50%, by weight, based on binding agent.

Another embodiment of this invention relates to a photographic element comprising (1) a support, (2) a photographic silver halide emulsion layer having a binding agent comprising gelatin and about 2.5 to about 50%, by weight, of carboxymethylated protein and, (3) a layer which is contiguous to said emulsion layer and has a binding agent comprising gelatin and a different hydrophilic colloid other than carboxymethylated protein.

Still another embodiment of this invention relates to a photographic element comprising (1) a support, (2) a photographic silver halide emulsion layer having a binding agent comprising gelatin and a different hydrophilic colloid other than carboxymethylated protein and, (3) a layer which is contiguous to said emulsion layer which has a binding agent comprising gelatin and about 2.5 to about 50%, by Weight, of carboxymethylated protein.

It is a significant feature of this invention that the hydrophilic colloids other than gelatin, as described herein, must be used together with gelatin in order to obtain the improved combination of properties described herein. This is evident from an examination of the following working examples, particularly Examples 1 and 2. Although hydrophilic colloids such as water soluble polyacrylamides have been used in binding agents to improve contrast, it could not have been expected that such materials could be used in combination with carboxymethylated proteins and gelatin to obtain a product which exhibits good photographic characteristics and resistance to abrasion.

The binding agent or vehicle employed in the practice of this invention comprises gelatin, which is a hydrophilic colloid, and at least two hydrophilic colloids other than gelatin. In practicing this invention a portion, usually about 40 to about 95%, by Weight, of the gelatin generally used in photographic emulsions and elements is replaced by at least two different hydrophilic colloids. One of the hydrophilic colloids employed for this purpose is a carboxymethylated protein. Carboxymethylated prO- teins which can be employed in the practice of this invention include those described in Gates et al. US. Pat. 3,011,890, issued Dec. 5, 1961. Some of the naturally occurring amino containing vegetable and animal proteins which can be carboxymethylated and used in practicing this invention include, for example, soybean protein, casein, edestin, glutin, blood albumin, egg albumin, caster bean protein, globulin, and the like. The carboxymethylation of such proteins can be conveniently accomplished by reaction upon the protein with an alpha halo fatty acid such as bromoacetic acid at a pH of 912, such as is obtained by the presence of an alkaline buffer material in the reaction mass. The degree of carboxymethylation is subject to variation but will usually be in the range of about to about by weight. Many proteins such as gelatin can ordinarily be carboxymethylated without any prior treatment and used in practicing this invention. However, some proteins contain naturally occurring sulfur compounds which are desirably destroyed or removed by oxidation prior to carboxymethylation. A suitable method which can be used for this purpose is treatment with hydrogen peroxide, as described in Lowe et al. US. Pat. 2,691,582, issued Oct. 12, 1954. The concentrations of carboxymethylated protein employed in practicing this invention is subject to wide variation and will, of course, depend upon the concentration of gelatin and other hydrophilic colloid. However, satisfactory results can generally be obtained with concentrations in the range of about 2.5 to about 50%, by weight, based on total binding agent. As already indicated, the carboxymethylated protein is used in combination with a different hydrophilic colloid other than gelatin. Suitable results can be obtained when the carboxymethylated protein comprises about 10 to about 90%, preferably about to about 70%, by weight, of the hydrophilic colloids other than gelatin in the binding agent. In the preferred case, the combination of hydrophilic colloids other than gelatin is a mixture of a carboxymethylated protein, e.g., carboxymethylated casein, with a water soluble vinyl polymer, e.g., polyacrylamide.

In practicing this invention a third ingredient of the binding agent is a hydrophilic colloid which is different from both the gelatin and the carboxymethylated protein. This hydrophilic colloid contains substantially no free amino or carboxy groups and is compatible with gelatin. The preferred hydrophilic colloid which is different from both the gelatin and the carboxymethylated protein is preferably a water soluble vinyl polymer such as a water soluble polyacrylamide. While particularly efiicacious resuts are obtained with water soluble polyacrylamide, other hydrophilic colloids can be used in the binding agent with carboxymethylated protein and gelatin. Such other hydrophilic colloid which can be employed with gelatin, and the carboxymethylated protein and with or in place of the preferred polyacrylamide, include any of the hydrophilic water permeable colloids, particularly the materials generally employed in the preparation of photographic silver halide emulsions as binding materials or vehicles, as examplified by colloidal albumin, cellulose derivatives, synthetic resins, particularly water soluble vinyl polymers and the like. Specific examples include water soluble polymers such as polysaccharides, e.g., dextran, as disclosed in US. Pat. 3,063,838, issued Nov. 13, 1962, vinyl polymers, e.g., poly-N-vinyl pyrollidones, as disclosed in US. Pat. 3,043,697, issued July 10, 1962, polyvinyl alcohol derivatives, e.g., acid derivatives such as succinoylated polyvinyl alcohol, as disclosed in Minsk and Abel US. Pat. 3,165,412, issued Jan. 12, 1965, proteins, protein derivatives, as described in US. Pat. 2,852,- 382, issued Sept. 16, 1958, cellulose derivatives, e.g., hydroxyetheyl cellulose, as disclosed in Illingsworth and Minsk U.S. Pat. 3,003,878, issued Oct. 10, 1961, and like compounds. Additional hydrophilic colloids that can be used in the practice of this invention are polymers containing repeating units having the following formula:

where R is a carbon chain of 1 to 5 carbon atoms substituted with 1-3 substituents having the formula -COXR2R3, X being R being hydrogen or lower alkyl, and R and R each being hydrogen or alkyl groups containing up to 5 carbon atoms, alkoxy substituted alkyl groups containing up to 5 carbon atoms or hydroxy substituted alkyl groups containing up to 5 carbon atoms. Preferred polymers of this type contain repeating units having the following formula:

where n is an integer from 1 to 5. Polymers of this type can also include monomeric units such as vinyl alcohol or other vinyl monomeric units including those represented by the formula:

- C 112- (EH- where Y is a photographically inert group such as hydroxy, an ester group such as acetoxy, an amide group such as N-alkyl Where the alkyl group contains up to 5 carbon atoms, carbamate groups such as where R and R are each carbon chains, preferably an alkylene, containing up to 5 carbon atoms. These additional polymers and copolymers can be prepared by any convenient method suitable for this purpose. For example, they can be prepared by treating the reaction product of poly(vinyl alcohol) and an ester of isocyanato monoor polybasic fatty acid with an amine. The reaction of the isocyanato compound with the poly(vinyl alcohol) may be partial or complete, as may be the reaction of the amine With the initial reaction product. A polymer of this type which can be employed in the practice of this invention is one which contains, in combined form, monomeric units of vinyl alcohol, vinyl carboxymethyl carbamate and vinyl -N ,8 hydroxyethylcarbamyl methylcarbamate. The concentration of hydrophilic colloid (not including gelatin and carboxymethylated protein) employed in the practice of this invention is subject to wide variation. However, the most suitable concentrations are generally in the range of about 2.5 to about 50, preferably about 30 to about 70%, by weight, based on the weight of the binding agent.

The carboxymethylated protein and hydrophilic colloid other than gelatin can be employed in one or more gelatin containing layers of a photographic silver halide element, including a gelatin, photographic silver halide emulsion layer. The concentration of carboxymethylated protein and hydrophilic colloid other than gelatin, based on total binding agent, is generally in the range of about to about 60%, by weight. Generally, a mixture of carboxymethylated protein with the other hydrophilic colloid is employed in photographic elements in gelatin photographic silver halide layers and/or other gelatin layers which are contiguous or adjacent to the photographic silver halide layer. However, for some applications it is desirable to use the carboxymethylated protein in one layer of a photographic element, e.g., in a gelatin photographic silver halide layer, and then use the other hydrophilic colloid in a contiguous or adjacent layer. This contiguous or adjacent layer can be between the carboxymethylated protein containing layer and the support or farther from the support. For certain applications this latter arrangement of layers may be preferred to using both the carboxymethylated casein and other hydrophilic colloid with gelatin in a single layer.

As already indicated, the water soluble polyacrylamides are the preferred polymeric hydrophilic colloids employed with gelatin and the carboxymethylated proteins in practicing this invention. Water soluble polyacrylamides can be obtained by polymerizing monomeric acrylamide using any procedure found suitable for this purpose. Typical methods for preparing water soluble polyacrylamides are described in Minsk et al. U.S. Pat. 2,486,191, issued Oct. 25, 1949; Lowe et al. U.S. Pat. 2,541,474, issued Feb. 13, 1951; U.S. Pat. 2,533,166, issued Dec. 5, 1950, and Allentolf et al. Belgian Pat. 651,507, issued Aug. 31, 1964. These water soluble polyacrylamides are characterized by a temperature below which their solutions in water precipitate polyacrylamide. Therefore, to get solubility, some of these compounds must be dissolved in water at elevated temperatures. In general, however, grams of water soluble polyacrylamide will dissolve in one liter of water at 100 F. Furthermore, the polyacrylamides can contain, in combined form, not only acrylamide groups but also acrylic acid or acrylamide groups, depending upon their process of preparation. The inherent viscosity of the water insoluble polyacrylamides employed in the practice of this invention is subject to variation but is preferably in the range of about 0.1 to about 0.6, as determined at 25 C. in water. As used herein, the term inherent viscosity is determined by the formula:

2.30 log 17,-

wherein 1 is the inherent viscosity, is the relative viscosity of water solution of the polymer divided by the viscosity of the water in the same units and at the same temperature and c is the concentration in grams (0.25) for a polymer per 100 cc. of solution.

Any of the gelatin, photographic silver halide emulsions can be employed in practicing this invention, including, for example, photographic silver halide emulsions used in X-ray and camera films and the like. Suitable photographic emulsions contain silver halides such as silver chloride, silver bromide, silver bromoiodide, silver chloroiciiide, silver chlorobromide and the like. Photographic emulsions which form latent images predominantly within the silver halide grains can be usefully employed in the practice of this invention. Such internal latent image emulsions are disclosed in Davey and Knott U.S. Pat. 2,592,250, issued Apr. 8, 1952. Particularly good results are obtained with silver bromoiodide emulsions in which the average grain size of the silver bromoiodide crystals is in the range of about 0.5 to about 5 microns.

The photographic compositions described herein can be coated on a wide variety of supports in preparing photographic elements. The photographic silver halide emulsions can be coated on one or both sides of the support which is preferably transparent and/or flexible. Typical supports are cellulose nitrate film, cellulose ester film, polyvinyl acetal film, polystyrene film, polyethylene, terephthalate film and other polyester film as well as glass, paper, metal, wood and the like. Supports such as paper which are coated with tit-olefin polymers, particularly polymers of u-olefins containing two or more carbon atoms, as exemplified by polyethylene, polypropylene, ethylenebutene copolymers, and the like, give good results.

The photographic emulsions described herein can be chemically sensitized with compounds of the sulfur group, noble metal salts such as gold salts, reduction sensitized with reducing agents, and combinations of these. Furthermore, emulsion layers and other layers present in photographic elements made according to this invention can be hardened with any suitable hardener such as aldehyde hardeners, aziridine hardeners, hardeners which are derivatives of dioxane, oxypolysaccharides such as oxystarch, oxy plant gums, inorganic hardeners such as chromium salts, and the like.

The photographic silver halide emulsions can also contain additional additives, particularly those known to be beneficial in photographic emulsions. For example, the emulsion can contain speed increasing compounds, for example, onium salts, such as quaternary ammonium or ternary sulfonium salts, polyalkylene glycols, thioethers, and the like. The photographic silver halide emulsions can be stabilized with mercury compounds, azaindenes, quaternary benzothiazolium compounds, hydroxy substituted aromatic compounds, and the like.

The photographic silver halide emulsions disclosed herein can also contain non-ionic, anionic and/or amphoteric coating aids. Some useful coating aids include, for example, saponin, alkyl substituted aryl oxy alkylene ethyl sulfonates of the type described in U.S. Pat. 2,600,- 831, issued June 17, 1952, maleoprimarates of the type described in U.S. Pat. 2,823,123, issued Feb. 11, 1958, taurine derivatives of the type described in U.S. Pat. 2,739,891, issued Mar. 27, 1956, and alkyl aminopropionates of the type described in U.S. Pat. 3,133,816, issued May 19, 1964. The emulsions and photographic elements described herein can contain incorporated developing agents such as polyhydroxy benzenes, aminophenols and 1,3-pyrazolidones. The photographic emulsions can also contain spectral sensitizers such as cyanines, merocyanines, complex (tri-nuclear) cyanines and complex (trinuclear) merocyanines, styryls and hemicyanines. These emulsions can be blue sensitive emulsions or they can be orthochromatic, panchromatic or X-ray emulsions. 4

The photographic silver halide elements described herein can contain absorbing dyes in the emulsion layer or in an auxiliary layer such as a layer coated between the support and the emulsion layer or the absorbing dyes can be included in both the emulsion and the auxiliary layer. These elements can also contain inert particles such as those often employed as matting agents in photographic elements. Suitable materials of this type include, for example, particles of silicon dioxide, glass, starch, polymethyl methacrylate, and the like. Such inert particles are often included in an emulsion layer and/or auxiliary layers coated over and/ or under an emulsion layer.

The photographic layers described herein exhibit an improved combination of properties, including good resistance to abrasion. The resistance to abrasion for the coated samples reported in the following examples is determined by drawing a pointed stylus slowly across the surface of the coating swollen with developer and recording the grams pressure required to puncture the surface. Photographic speed (sensitivity), as reported in the following tables, is indicated as a function of the exposure necessary to give a density of 0.20 above background fog and is relative with respect to the control in each case.

This invention can be further illustrated by the following examples of preferred embodiments thereof although it will be understood that these examples are not intended to limit the scope of the invention unless otherwise specifically indicated.

7 EXAMPLE 1 As already indicated, the replacement of part of the gelatin in a binding agent in a photographic silver halide emulsion or emulsion layer with a combination of at least two different hydrophilic colloids gives a product having a superior combination of properties. To illustrate, a coarse grained gelatino silver bromoiodide emulsion of the type normally used in medical X-ray film is coated on conventional cellulose acetate film support. The coating contains mucochloric acid and chrome alum hardeners and an alkyl substituted aryl oxy alkylene sulfonate coating aid. The silver bromoiodide emulsion is coated at a coverage of 430 mg. of silver and 410 mg. of gelatin per square foot of support. The silver bromoiodide emulsion is coated over a gelatin layer containing about 450 mg. of gelatin per square foot support. Over the silver bromoiodide emulsion layer is coated a gelatin layer containing about 150 mg. of gelatin per square foot of support. This sample (Coating No. 1) contains only gelatin as the binding agent and serves as the control.

Additional samples (Coatings Nos. 2-6) are prepared using the above procedure except that varying concentrations of carboxymethylated casein, prepared as described in Gates et al. U.S. Pat. 3,011,890, issued Dec. 5, 1961, and/ or polyacrylamide (inherent viscosity 0.30 in water at 25 C.) are incorporated into the silver bromoiodide emulsion layer at the concentration listed in the following table.

Each of the coated samples is exposed on an Eastman Ib sensitometer and processed through an automatic proc- I essing machine of the type described in Russell US. Pat. 3,147,090, issued Sept. 1, 1964, using a hardening developer having the following formula:

Grams 1 phenyl pyrazolidone 1.5 Hydroquinone Sodium sulphite, desiccated 65 Sodium metaborate octahydrate 40 Sodium hydroxide 1 Potassium bromide 5 Tetrasodium ethylene diamine tetracetate 3 Glutaraldehyde bis(sodium-bisulfite) Water to make 1 liter.

The resistance to abrasion for the samples is determined using the procedure described hereinbefore. The speed, gamma and net fog are also determined for the coated samples. The results are as follows:

carboxymethylated proteins, such as carboxymethylated gelatin, carboxymethylated soybean protein, and the like. In addition, the water soluble polyacrylamide can be replaced in the above procedure by other hydrophilic colloids, such as hydro-xy ethyl cellulose, polyvinylpyrrolidone, succinoylated polyvinyl alcohol, dextran, and the like. As previously pointed out, it is also possible to incorporate the carboxymethylated casein into the emulsion layer and put the polyacrylamide in the gelatin overcoat or undercoat. Alternatively, the carboxymethylated casein can be put in the gelatin overcoat or undercoat and the polyacrylamide put into the emulsion layer.

Additional improvements in the coatings can also be achieved by adding materials such as absorbing dyes. For example, when a yellow sulfonated benzoxazole pyrazolone absorbing dye of the type disclosed in Heseltine US. Pat. No. 3,148,187, issued Sept. 8, 1964, is added to the emulsion layer in Coating 6 of the above procedure, there is obtained a photographic element having better image sharpness than a similar coating in which the absorbing dye is omitted. When this increase in image sharpness is desired, the absorbing dye can be added to the emulsion layer, even though it diffuses into the gelatin undercoat during coating. The dye can be coated at any suitable coverage, e.g., 4 mg. of absorbing dye per square foot of support.

EXAMPLE 2 A coarse grained gelatino silver bromoiodide emulsion of the type normally used in medical X-ray film is coated on a conventional polyethylene film support. The coating contains mucochloric acid and chrome alum hardeners and an al-kyl substituted aryl oxy alkylene ethyl sulfonated coating aid. The silver bromoiodide emulsion is coated at a coverage of 430 mg. of silver and 410 mg. of gelatin per square foot of support. Over the silver bromoiodide emulsion is coated a gelatin layer containing approximately 150 mg. of gelatin per square foot of support. Carboxymethylated casein, prepared as described in Gates et al. US. Pat. 3,011,890, issued Dec. 5, 1 961, is incorporated into the emulsion layer in one sample of the coating without polyacrylamide (Coating No. 1) and with polyacrylamide (inherent viscosity of 0.30 in water at 25 C.) (Coating No. 2). The concentrations of carboxymethylated casein and polyacrylamide are set forth in the following table. Samples of each of the coatings are exposed, processed and tested as described in Example 1. The following results are obtained:

TABLE 1 TABLE 2 Carboxy- C Y- methylated Polyacmethy a e a casein rylamide Resistcasein rylamide Res1st- (g-lmole (g./mole (3 11- t ance t (g./mo1e (g.[rnole Con- Net ance to Coating No. silver) silver) Speed tra t fog abrasion Coating No. silver) silver) Speed trast fog abrasion 1 (control) None N n 2 2, 0 03 2 1 2 N011e 132 25 2 N 115 245 1 2g 50 2 11 11 129 48 None 44 1-11 2. 13 16 11 22 155 2. 80 18 21 11 11 132 2.60 .15 27 EXAMPLE 3 l1 5 126 2. 60 17 28 From the results shown in Table 1, it can be seen that the use of the combination of hydrophilic colloids as disclosed herein, in a binding agent gives photographic materials exhibiting a good combination of speed, contrast and resistance to abrasion, even upon processing in automatic equipment. Furthermore, as shown by the results obtained with Coating 3, the use of polyacrylamide alone with gelatin in photographic silver halide emulsions substantially downgrades resistance to abrasion. It could not have been expected that the use of this material in combination with carboxymethylated proteins, such as carboxymethylated casein, would give photographic silver halide emulsion layers exhibiting a good combination of photographic properties and resistance to abrasion as shown by the results obtained with Coatings 4-6.

Similar results are obtained when the carboxymethylated casein in the above procedure is replaced by other As previously pointed out, the combination of hydrophilic colloids including a carboxymethylated protein, can be incorporated into a gelatin layer which is coated over an emulsion layer. To illustrate, a coarse grained gelatino silver bromoiodide emulsion of the type normally used in medical X-ray film is coated on conventional cellulose acetate film support. The emulsion coating contains mucochloric acid and chrome alum hardeners and an alkyl substituted aryl oxy ethyl sulfonated coating aid. The silver bromoiodide emulsion is coated at a coverage of 390 mg. of silver and 660 mg. of gelatin per square foot of support. Over the emulsion layer is coated a gelatin layer containing about mg. of gelatin per square foot of support. This photographic element (Coating No. 1) contains only gelatin as the binding agent and serves as the control.

Another coating (Coating No. 2) is prepared using the above procedure except that the gelatin layer coated over the emulsion layer contains both carboxymethylated casein, prepared as described in Gates et al. U.S. Pat. 3,011,890, issued Dec. 5, 1961, and polyacrylamide (inherent viscosity of 0.30 in water at 25 C.). The coverages in the gelatin layer over the emulsion layer are 91 mg. of gelatin per square foot of support, .13 mg. of carboxymethylated casein per square foot of support and 13 mg. of polyacrylamide per square foot of support.

Samples of each coating are exposed in an Eastman Ib sensitometer. The samples are developed at 65 F. for 6 minutes using Kodak D-19 developer in a deep stainless steel tank. The photographic speed, gamma, fog and resistance to abrasion as tested as in Example 1. The results are as follows:

In addition to determining the above characteristics, samples of each coating are also tested for static resistance. Prior to exposure, the coatings are conditioned at -30% relative humidity and put in contact with an X-ray fluorescent screen and rolled under a pressure of 30 pounds per square inch. The screen and film samples are then separated and discharged by contacting with a grounded 90 metal frame which gives a well defined static pattern. After development, the samples are visually observed and assigned a static resistance number from 0-10, 0 indicating no static with increasing degrees of static being given a progressively higher number. When subjected to this test, Coating 1 is rated at 7, indicating a moderate to heavy static pattern while Coating 2 is rated at 5, indicating a much greater resistance to static.

Thus, by the practice of this invention there is provided photographic silver halide emulsions and elements exhibiting an improved combination of photographic and physical properties. This invention enables one skilled in the art to take advantage of the improved physical properties, for example, resistance to abrasion, without substantially down-grading photographic properties such as sensitivity and contrast. The photographic elements described herein, by virtue of their excellent combination of physical and photographic properties, are particularly useful for processing in automatic equipment.

Although the invention has been described in considerable detail with reference to certain preferred embodiments thereof, it Will be understood that variations and modifications can be effected without departing from the spirit and scope of the invention as described hereinabove and as defined in the appended claims.

I claim:

1. A photographic silver halide emulsion having a binding agent comprising gelatin and at least two other hydrophilic colloids, one of the said other colloids being carboxymethylated protein at a concentration in the range of about 2.5 to about 50%, by weight, based on binding agent, and the other of said hydrophilic colloids being compatible with gelatin and selected from the group consisting of a polyacrylamide, polysaccharides, and poly-N- vinyl pyrrolidone.

2. The photographic emulsion of claim 1 in which the other hydrophilic colloids comprise a mixture of a water soluble poly-N-vinyl pyrrolidone with carboxymethylated casein.

3. The photographic emulsion of claim 1 in which the other hydrophilic colloids comprise a mixture of carboxymethylated casein with a water soluble polyacrylamide having an inherent viscosity in the range of about 0.1 to about 0.6.

4. A photographic element comprising a support and a layer having a binding agent comprising gelatin and at least two other hydrophilic colloids, one of said other hydrophilic colloids being carboxymethylated protein at a concentration in the range of about 2.5 to about 50%, by weight, based on binding agent, and the other of said hydrophilic colloids being compatible with gelatin and selected from the group consisting of 21 polyacrylamide, polysaccharides, and poly-N-vinyl pyrrolidone.

5. The photographic element of claim 4 in which the other hydrophilic colloids comprise a mixture of carboxymethylated casein with water soluble poly-N-vinyl pyrrolidone.

6. The photographic element of claim 5 in which the other hydrophilic colloids comprise a mixture of carboxymethylated casein with a water soluble polyacrylamide having an inherent viscosity in the range of about 0.1 to about 0.6.

7. The photographic element of claim 4 in which the layer having the binding agent comprising gelatin and at least two other hydrophilic colloids is a photographic silver halide emulsion layer.

8. A photographic element comprising (1) a support, (2) a photographic silver halide emulsion layer having a binding agent comprising gelatin and at least two other hydrophilic colloids, one of said other hydrophilic colloids being carboxymethylated protein at a concentration in the range of about 2.5 to about 50% by weight, based on binding agent, and the other of said hydrophilic colloids being compatible with gelatin and selected from the group consisting of a polyacrylamide, polysaccharides, and poly-N-vinyl pyrrolidone and (3) contiguous to said emulsion layer, a layer having a binding agent comprising gelatin and at least two other hydrophilic colloids, one of said other hydrophilic colloids, being carboxymethylated protein at a concentration in the range of about 2.5 to about 50%, by weight, based on binding agent, and selected from the group consisting of a polyacrylamide, polysaccharides, and poly-N-vinyl pyrrolidone.

9. The photographic element of claim 8 in which the contiguous layer is farther from the support than the photographic silver halide emulsion layer.

10. The photographic element of claim 4 in which the layer having a binding agent comprising gelatin and at least two other hydrophilic colloids is a layer which is contiguous to a photographic silver halide emulsion layer and is farther from the support than said emulsion layer.

11. The photographic element of claim 8 in which the other hydrophilic colloids in the photographic emulsion layer and in the contiguous layer comprise a mixture of carboxymethylated casein with water soluble polyacrylamide having an inherent viscosity in the range of about 0.1 to about 0.6.

12. The photographic element of claim 9 in which the other hydrophilic colloids in the photographic emulsion layer and in the contiguous layer comprise a mixture of carboxymethylated casein with water soluble polyacryl amide having an inherent viscosity in the range of about 0.1 to about 0.6.

13. A photographic element comprising (1) a support, (2) a photographic silver halide emulsion layer having a binding agent comprising gelatin and about 2.5 to about 50%, by weight, of carboxymethylated protein and (3) a layer which is contiguous to said emulsion layer and has a binding agent comprising gelatin and a different hydrophilic colloid other than carboxymethylated protein selected from the group consisting of 21 polyacrylamide, polysaccharides, and poly-N-vinyl pyrrolidone.

14. A photographic element comprising (1) a support, (2) a photographic silver halide emulsion layer having a binding agent comprising gelatin and a different hydrophilic colloid other than carboxymethylated protein selected from the group consisting of a polyacrylamide, polysaccharides, and poly-N-vinyl pyrrolidone and, (3) a layer which is contiguous to said emulsion layer and has a binding agent comprising gelatin at about 2.5 to about 50%, by weight, of carboxymethylated protein.

15. The photographic element of claim 13 in which said hydrophilic colloid in (3) is water soluble polyacryl- 1 l amide having an inherent viscosity in the range of about 0.1 to about 0.6.

16. The photographic element of claim 14 in which said hydrophilic colloid in (2) is water soluble polyacrylamide having an inherent viscosity in the range of about 0.1 to about 0.6.

17. A photographic element comprising (1) a support, (2) a photographic silver halide emulsion layer and (3) a layer which is contigous to said emulsion layer and has a binding agent comprising gelatin and has at least two other hydrophilic colloids, one of said other hydrophilic colloids being carboxymethylated protein at a concentration in the range of about 2.5 to about 50%, by weight, based on binding agents, and the other of said hydrophilic colloids being compatible with gelatin and selected from the group consisting of a polyacrylamide, polysaccharides, and poly-N-vinyl pyrrolidone.

References Cited UNITED STATES PATENTS NORMAN G. TORCHIN, Primary Examiner R. E. FICHTER, Assistant Examiner US. Cl. X.R. 

